[Fast determination of andrographolide and dehydroandrographolide in Xiaoyanlidan Tablets by microemulsion electrokinetic chromatography].

A microemulsion electrokinetic chromatography (MEEKC) method for the determination of andrographolide and dehydroandrographolide in Xiaoyanlidan Tablets was established. The MEEKC method involved the use of sodium dodecyl sulfate (SDS) as surfactant, ethyl acetate as organic solvent and 1-butanol as co-surfactant. The effects of several factors such as the acidity and concentration of borate buffer, SDS and 1-butanol contents were investigated. The optimized composition (by mass) of microemulsion system are 0.5% ethyl acetate--0.6% SDS--6.0% 1-butanol--92.9% 30 mmol/L sodium tetraborate buffer (pH 9.5). This system allowed a useful and reproducible separation of the analytes to be achieved in less than 6 min. The proposed method is a simple, fast and sensitive method for the determination of andrographolide and dehydroandrographolide in Xiaoyanlidan Tablets.